The Willamette Meteorite

One of the treasures of the American Museum of Natural History’s permanent collection is a large piece of extra-terrestrial rock called the Willamette Meteorite. At 15.5 tons, it is the largest meteorite ever found in the United States, and the sixth largest in the world.

The Willamette Meteorite is mostly composed of iron and nickel, and like all iron meteorites, it was formed billions of years ago when the solar system was still forming out of cosmic dust. Gravity caused these dust particles to come together to form protoplanets and heavier metals like iron and nickel sank into the interior to form the core. Some time later, this protoplanet must have collided with another planetary body, causing it to fracture, sending chunks of rocks rich in iron and nickel out into space.

Credit: Mike Cassano/Flickr

The pieces of the protoplanet continued to circle the sun for the next several billion years, until about 17,000 years ago, when the orbits of the earth and that of one of the rocks—which will eventually become the Willamette Meteorite—intersected. The meteorite crashed into the earth at more than 64,000 kmph, somewhere in an ice cap in western Canada.

Over the centuries, moving glaciers slowly transported the meteorite to Montana to the vicinity of an ice barrier that had formed across the Clark Fork River. This barrier had ponded a huge amount of water at the Lake Missoula. Just as the meteorite reached the area, the ice dam crumbled releasing one of the largest floods ever documented. Trapped in ice, the meteorite floated down the Columbia River until its ice case broke and the meteorite sank into the river bottom near the modern day city of Portland.

At the end of the last Ice Age, as the waters ebbed, the meteorite became exposed to the elements. Over thousands of years, rainwater mixed with iron sulfide in the meteorite produced sulphuric acid, which slowly dissolved portions of the rock creating hollows on its surface.

Two boys sit inside the hollows of the Willamette Meteorite.

The meteorite was first discovered by the Clackamas Chinook people, who lived in the Willamette Valley of Oregon before the European settlers arrived. The Clackamas named the meteorite "Tomanowos", believing the rock to be a representative of the Sky People and exemplifying a union between the sky, earth and water. For the Clackamas, Tomanowos was sacred. They revered it as a spiritual being with powers to heal and empower people of the valley. They used the rock in various ceremonies, using the water collected in the meteorite's crevices to cleanse and purify themselves. Tribal hunters, before they went out to hunt, dipped their arrowheads in the water.

In 1902, a miner named Ellis Hughes saw the meteorite, and recognizing the rock’s significance, secretly moved it to his own property—a task that took three months. Once the meteorite was on his land, he began charging admission to view the “Willamette Meteorite.” The land where the meteorite originally stood belonged to the Oregon Iron and Steel Company. When the theft was discovered, the rock’s legitimate owner sued for and won possession of the meteorite. The company sold the meteorite to Mrs. William Dodge, who then gifted it to the American Museum of Natural History in New York.

Credit: Wikimedia

The Willamette Meteorite remained on display at the museum for nearly a century, when in 1999, the Confederated Tribes of the Grand Ronde Community of Oregon (CTGRC), a confederation of Native American tribes, demanded that the revered Tomanowos be returned to them. A case was filed against the American Museum of Natural History, and later that year, an agreement was reached according to which the meteorite remained at the museum but tribal members were allowed to conduct a private ceremony around the meteorite once a year. A section of the meteorite that was cut from the larger rock was also returned to the CTGRC.